Number 216 - May 2001

USB Survival Guide
by Jan Axelson, Amateur Computer Group of New Jersey, Sep 2000 ACGNJ News Making the most of USB peripherals while minimizing problems
So you're in the market for a new peripheral. Maybe it's a printer, scanner, external drive, or camera. If so, chances are good that many of the products you look at will have a USB port in place of the parallel, serial, SCSI, or other port used by peripherals in the past. In most cases, USB is the way to go. It's convenient, easy, and fast. But because it's a new interface, it's not yet foolproof, and a little prevention can go a long way in saving you from possible hassles. I'll show you how. But first, a little back ground...     PC and peripheral makers are phasing in the Universal Serial Bus (USB) as a replacement for the ports that have been with the PC since its beginnings. If you're running Windows 98 or Windows 2000, you can use USB for your keyboard, mouse, modem, external disk drives, printer, scanner, cameras, and more. Just about any peripheral that once used a parallel port or RS-232 serial port is likely to have a USB version available now.     What's so great about USB? When you attach a new device, Windows detects it and installs the driver software for you. You don't have to worry about finding a free IRQ (interrupt request line) because all devices share one IRQ assigned to the USB host controller. You don't have to find a free expansion slot be cause USB devices connect out side the box. With inexpensive hubs, you can attach pretty much as many devices as you want (though there are practical limits to how many devices can communicate on the bus at the same time). USB's speed is comparable to the parallel port's fastest modes, and this will increase 40x with the introduction of hardware that supports the new 2.0 specification's fast mode. Another point in USB's favor is that the older ports are being eliminated from new PCs and eventually won't be an option, while new interfaces like IEEE-1394 (Firewire) aren't widely available yet. The only snag is that USB's simplicity for users means increased complexity for the developers who design and program USB devices and the software drivers that control them. Also, because USB is new, developers don't have a lot of experience with it. And although Windows 98 and 2000 have good low-level support for USB communications, developers must still write device drivers for the many peripherals that don't have class drivers provided by Windows.	Of course, users don't care about any of this. You just want something that works! But the reality is that some USB devices, on some machines, just don't work as advertised. If you're in the market for a peripheral, following these recommendations will save you possible grief:     1. Before you buy, check the webboards for comments and possible fixes. Two excellent sources for user information are the USB Implementers Forum's Public Newsgroup (www.usb.org/ forums/ retail/ webboard.html ) and USBMan's USBTalk webboard (www.usbman.com). If you see a lot of users tearing their hair out in frustration with a product you're thinking about buying, look else where.     2. If you have a problem with a device, the first place to check is the manufacturer's website for updated drivers and other tips. Driver fixes are very common!     3. If you can't get some thing working, take or send it back and try something else. Don't spend a lot of time trying to get some thing going. Sometimes the problem is a flawed hardware design or software driver that the vendor is unwilling or unable to do anything about. In that case, there's really not anything you can do.On a more positive note, vendors are becoming more diligent about testing their products rigorously before they're released. More and more devices undergo compliance tests that exercise not just data transfers but also things like what happens when a user yanks the cable unexpectedly. Many manufacturers also participate in Plugfests, where every one hooks their devices to the same PC to find out if they all can co-exist. The short answer is that USB is the right choice most of the time. But for now, when selecting a peripheral, a little caution is prudent!     Jan Axelson (jan@lvr.com) is the author of "USB Complete: Everything You Need to Develop Custom USB Peripherals". Jan grew up in North Plainfield and Plainfield, NJ and graduated from Plainfield High (class of '67). Her website is www.lvr.com.
Number 216 - May 2001